Question

Agricultural researchers want to know if there is a difference in the amount of corn harvested when two different fertilizers are used. Consider the following observational study and experiment:

Observational study
The researcher chooses thirty corn plants which were fertilized with either fertilizer A or fertilizer B. After one season, she records the amount of corn harvested for each plant.

Experiment
Another researcher selects thirty corn plants and randomly assigns them to either fertilizer A or fertilizer B. After the end of the season, she records the amount of corn harvested for each plant.

Which of the two, the given observational study or the given experiment, will give better information about the relationship between the type of fertilizer and the amount of corn harvested? Please explain your answer.

Answer 1

Answer to the question)
The experimental design is a better approach here and would provide better information about the relationship between the type of fertilizer and the amount of corn. In observational study the amount of fertilizer used, the timing and other environmental factors are unknown and uncontrollable

In case of experimental design, one can actually control all the other possible influencing factors and hence get an unbiased result about the relationship of fertilzers and corn harvest

Experimental design allows the researcher to intervene and control the environment, so the main variables of research can be observed under supervision and control. Hence in all ways this is a better design for the given scenario